The long-term goals of this research is to elucidate the neural mechanisms underlying cognitive processes of motor behavior. Experimental psychological studies, neurophysiological recordings, and modelling are pursued to achieve these goals. Psychological studies are carried out i both human subjects and rhesus monkeys. The tasks are cognitive in nature and are focused on paradigms of mental rotation and memory scanning. Electrophysiological recordings of the activity of single cells in motor and other areas of the cerebral cortex are then performed in monkeys behaving in these tasks in order to elucidate the brain mechanisms involved in mental rotation and memory scanning. This experimental arrangement provides for a direct study of the relations between neuronal populations and behavior. The activity in these neuronal populations is modelled in order to visualize the representation of spatial motor information and its transformations demanded by the tasks. Finally, information concerning synaptic interactions among neurons in a given area is obtained by using cross-correlation analyses of data recorded simultaneously from 7 independently movable microelectrodes.